Metamorphosis/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A boy, Tim, is standing outdoors. A butterfly flies past him. A robot, Moby, chases the butterfly with a butterfly net. TIM: Hey, Moby. Moby catches Tim's head in the butterfly net. The butterfly flies past his face and gets away. TIM: Grrrr. Tim reads from a typed letter. TIM: Dear Tim and Moby, How exactly does a caterpillar become a butterfly? From, Chris. TIM: That change from caterpillar to butterfly is part of something called a metamorphosis. Insects like butterflies and mealworms go through what we call a complete metamorphosis. They start out as an egg laid by an adult butterfly. An image shows several butterfly eggs. TIM: A wormlike larva hatches from the egg and starts eating. MOBY: Beep beep. TIM: Right. That's the caterpillar. An animation shows a freshly hatched larva, a caterpillar, taking bites from a leaf. TIM: The larva becomes a pupa. During the pupa stage, adult tissues and organs form inside a protective casing. An animation shows a cross-section of a pupa, or cocoon, hanging from a tree. The caterpillar inside it is changing form. TIM: Finally, the animal emerges from its hard shell as an adult. An animation shows a freshly emerged butterfly. It takes off and flutters by Tim and Moby. TIM: Look. The adult butterfly looks really different from the original larva. Tim holds up a poster with side-by-side images of a caterpillar and a butterfly. Moby swipes at the flying butterfly with his net. TIM: Moby. Moby misses. The butterfly flies away. TIM: Insects like the damselfly are different. They undergo incomplete metamorphosis. An animation shows a damselfly perched on the edge of a birdbath. TIM: A damselfly starts out as an egg. An image shows several damselfly eggs attached to the underwater part of a reed. TIM: The egg hatches into a nymph that lives in water and breathes with gills. An image shows a nymph resting on a reed, with its head above the water's surface. TIM: The nymph eventually comes out of the water, sheds its skin, and sprouts tiny wings. An image shows an adolescent damselfly. It looks as Tim describes. TIM: After shedding its skin a few more times, it becomes an adult damselfly. An animation shows an adult damselfly, spreading its large wings as it crawls on a branch. It buzzes and flies off. MOBY: Beep. TIM: No. Insects aren't the only things that can undergo metamorphosis. Some other animals, like certain amphibians, mollusks, and crustaceans can do it, too. Just ask a frog. When a frog is born from an egg, it's a tadpole, which is kind of like the larva stage in insects. It has gills to breathe in the water, like fish. An animation shows a clump of frog eggs. A tadpole emerges from one of the eggs. TIM: It swims around for a while, getting nutrients and growing bigger. The tadpole becomes larger and more froglike. TIM: Eventually, a tadpole grows front legs, back legs, and a set of lungs. The animation shows the transformation Tim describes. TIM: Finally, a young frog will lose its tail. It actually gets absorbed by the body. The tadpole becomes a small frog. A damselfly hovers near Tim and Moby. Moby attempts to catch it with his net. He misses, and the insect moves closer to Moby's face. After hovering for a moment, it flies repeatedly into Moby's head. Moby covers his face and ducks. MOBY: Beep. The damselfly continues attacking Moby. TIM: I'm not helping you. You were asking for it.